Heat exchange tubing



Dec. 16, '1952 l. H. coHLER 2,621,903

HEAT EXCHANGE TUBING Filed July 2, 1949 O L um @Y y Patented Dec. 1K6,1.9542

UNITED-f STA-TES PATENT OFFICE HEATEX-'CHANGE'TUBING Irving H; Cohler,Chicago, Ill. Appiitatibn J1y2; 1949, serial No. 102,791

6 Claims.- 14 My invention Vrelates-to heat-[exchange apparatus -andl isparticularlyv concerned with v*heat eX- change tubing, particularly foruser in liquid' coolers and heaters,condensers, heating and coolingcoils, and heatpexchangers generally;

Various types of heat exchange equipment, and tubing for use or inconnection therewith, have heretofore been proposed Yand. gone intolwidespread'nse'in theart. By and large, these have ciencylA'typical-"caseinvolves'watercooling ap- A paratusV where-thepossibilityofjcontaininaticn'of v theA 4water-*by leakage-fromthepiping" carrying the refrigeratingor coolingrnediuin -befrel duced-toVaqznractical4 minimum'withoit," h'wever,

undulyy Aiinpairing the heat transfer eniciency or*j thelsystem.-Efforts heret'oformadsatisiactorily to meet this Situatin havrfailedgenerauy betransferofothersuggested equipment.'

Inlgeneral,my` invention comprises the' production .ofy novel-heatexchange Atubin;g""cor1c'1'p ing :at

least twovindividualmet'alA tubes which maybe Yof the` same lordifferent f' cross *sectional sie and shapeQlmade: cfa metal of good'heatco'ndiictivity for example,-copper,-copper alloys,"stainlessAsteel, 'n or the like, said tubesbeingof generallyfrundd cross'section,said-tubes being disposedin `parallel longitudinal lrelationship with"Aeach' 'other'. For most purposes; only twoindividu'al" tubesare utilizedand,ly most advantageously, they areV of conventionaltype;namely;-theirinneriand'ut'er peripherieslbeingcircularin cross section? For "certaintypesf ofnheatfexchange problems;` three" or more individuali metaltubes' may be utilized "and,

in such cases, f all ofi saidl tubes 'fare-disposed longitudinal! or`parallel relationship with Veach other. i Theouter surfaces? ofthe twovtubes, or the outer. surfaces 'ofthe adjacent -tubes *many S50 series ofmore than two tubesgfarein contact'with eachother over onlyl a portion,-Uparticularly over only a` small fractiomof theirfsurf-aceareas andAvthe adjacent tubes `are'united to-each 'other over onlyA a smallarea'invimmediate juxtarosit-ionL to outer peripheries of which arecircular in cross section, the Contact between such tubesgifvthey' areof equal diameter; is theoretically a line contact although, as apractical proposition,l it is greater than that. In any event, the areaof cone tact between adjacent tubes is small in relation tothe totalityof their external surfaces.v`v

good thermal conductivityas; for example, cop;

per, copper alloys, stainless steel, or the like'.` The banding may takethe formof round or flat wiref of relatively rwide indivdualsheets'orpreformed tubes, but it is particularly desirablethat it be of iiatstrip-material. Thebanding may take Vari ious forms,v asdescribedhereafter in greater deltail rin` conjunction with the drawing, and it"should contact the tubes over a substantial area, preferably from about50% toV about 75%, of 'their external surfaces.` It serves to provide ahigh Ydegree of heat transfer surface from one'tube' toanother with asubstantially minimum amountof physicalcontact between the"individualtubes'f- The construction issuch as to' leave 01 psitelydis`posed'air spaces den'ed by portions of the outerV periphery of each ofvsaid tubes and the inner surfaces offsaidbanding;

The invention will be particularly clearlyV under-- stood in the lightof the accompanying `'drawing which' illustrates various 'embodiments ofmy invention'and wherein Fig; l is an elevational View of one embodimentof heat exchangetubing vmade in accorda ance with my invention;

Fig. 2 is an elevational view of a'second embodiment of my invention;

Fig. 3 is an elevational view of a third embodiment of'my invention;

Fig. 4 is an elevational view of a fourth'embodment of my invention;

Fig. 5 is acrosssectional view taken along "the line 5`-5 of Fig; 1;

Figf is af'cross sectional'viewr of another `embodiment of my invention;

, Fig 7 isa cross sectional'view of lstilll another 1 embodiment of myinvention;

Fig. 8 shows heatexhange tubing; made-in accordance with my' invention,wound into fa* coil; and

Fig. s s'hows a `stm further modified emmen--A ment utilizing certainvfeatures" of my invention;

disposed in parallel longitudinal relationship to each other and unitedor bonded together as shown at I2 and I3. The union or bonding may becontinuous along the length of the tubes or it may be at spacedintervals. Two lines of bonding may be employed or the bonding may bealong only one line. It is most advantageous that the bonding be alongtwo lines, as shown, that it be continuous or substantially so. Thebonding may be accomplished by welding, by means of solder or likematerials or in any other suitable manner. In any event, it will benoted that the tubes are united to each other over only a very smallarea immediately adjacent to their areas of contact. A continuous flatmetallic strip I4 is wound helically around the tubes to form anencompassing metallic banding, the windings of said banding beingslightly spaced from each other to provide apertures or spaces I6. Asshown more particularly in Fig. 5, the banding I4 is bonded to the tubesat I'I, I8, I9 and 2|. This bonding need not be at al1 of said areasand, as described in connection with the bonding at I2 and I3, it may becontinuous or discontinuous along the width of each winding of saidbanding. It is particularly desirable that the bonding area encompasssubstantially the entire surface between the banding and those areas ofthe tubes with which said banding is in contact. This may beaccomplished by welding, soldering or like operations. The constructiondescribed provides oppositely disposed separate air spaces 22 and 23defined by portions of the outer periphery of each of the tubes and theinner surfaces of said banding. Any leakage in either of the tubes I orII would be readily manifested through apertures or spaces I6.

In Fig. 2, the construction is similar to that of Figs. 1 and 5 exceptthat the metallic banding 24 is helically wound in such a manner as to'leave no space between the successive windings, and holes or apertures26 are provided in said banding in lieu of spaces I6 in the embodimentof Figs. 1 and 5.

Fig. 3 shows a construction wherein individual metallic bands 21, spacedfrom each other, are utilized to form the encompassing metallic banding,and Fig. 4 shows a construction similar to that of Fig. 3 except thatthe individual bands 28 are not spaced from each other and are providedwith holes or apertures 29.

In Figs. 3 and 4, instead of using a plurality of individual bands, Imay employ a single band made from a single, relatively wide sheet ofcopper, copper alloy or other metal of good heat conductivity. Thesingle sheet of metal may be wrapped around the tubing and suitablybonded thereto to form the encompassing metallic banding, or the bandingmay comprise a preformed tube which may be slipped over the tubing andsuitably bonded thereto, as described above.

Fig. 6 shows an embodiment of my invention wherein three tubes, 3I, 32and 33, are employed, the adjacent tubes of which are bonded to eachother at 34, 36, 31 and 38. The encompassing metallic banding 39 maytake any of the illustrative forms shown in Figs. 1 to 5, inclusive, andbonding may be effected at several areas as, for example at 4I, 42, 43and 44. In the embodiment of Fig. 6, it will be noted that the banding39 is crimped inwardly adjacent the air spaces, preferably at all fourpoints 45, 46, 41 and 4B. This crimping may be accomplished by anysuitable tool or equipment and serves to improve the thermal efficiencyof the unit. It

will be understood that, if desired, this crimping feature may beemployed in any of the embodiments of Figs. 1 to 5, inclusive.

Fig. '7 shows a construction wherein the tubes 49 and 5I are ofgenerally elliptical configuration and are in contact with each otheralong a line drawn through their major or transverse axes. Bonding andbanding may be similar to that described above.

In Fig. 8, I show the tubular construction of my invention arranged inthe form of a coil 52. In this connection, it should be noted that thecoil may be made in various ways and by various sequences of steps. Theuse of such coils is especially advantageous in various heat exchangearrangements and such coils comprise an important, though limited,embodiment of my invention.

In the construction of Fig. 9, it will be noted that each convolution ofthe coil 53 is not provided with separate banding. Rather, the banding54 is wound or wrapped around the preformed coil of the two or moreindividual tubes bonded together as described above, or bonded togetherat any other suitable stage in the manufacture of the iinished coil, andsaid encompassing metallic banding is united or bonded to said tubes andpreferably crimped as shown a 55.

While my invention has been described in detail, no unnecessarylimitations should be read thereinto, the scope of the invention beingset out in the appended claims.

What I claim as new and desire to protect by Letters Patent of theUnited States is:

1. A prefabricated heat exchange tubing structure comprising at leasttwo individual metal tubes of generally rounded cross section, all ofsaid metal tubes being disposed in essentially a single plane and inparallel longitudinal relationship with each other, the outer surfacesof only the adjacent metal tubes being in contact with each other oversubstantially only a line contact, each of said metal tubes beingmetallically and rigidly bonded to its adjacent metal tube over only asmall area immediately adjacent their lines of contact to provide a rstpath of good thermal conductivity between the adjacent metal tubes andto give rigidity tothe heat exl change tubing structure, and metallicbanding of good thermal conductivity encompassing said metal tubes,contacting said metal tubes over a substantial area of their externalsurfaces and being metallically and rigidly bonded to said metal tubesto provide a second path of goodV thermal conductivity between the metaltubes and also to give rigidity to the heat exchange tubing structure,there being oppositely disposed separate air spaces defined by portionsof the outer surfaces of each of said metal tubes and the inner surfacesof said metallic banding for collecting liuid from said metal tubes inthe event of rupture of any of said metal tubes within the confines ofsaid metallic banding and adjacent the air spaces and for effectivelypreventing intermingling of the fluids in said metal tubes upon suchrupturing of any of said metal tubes, said encompassing metallic bandinghaving apertures communicating with said air spaces so that leakage fromsaid metal tubes into any of said air spaces upon rupture of any of saidmetal tubes may be readily detected through` amanece 2. A:.prefabricated` .heat l.exchange :tubing1 structure.; comprising.y atleast. two .individual metal tubes :of generally rounded cross section,all of said.metaltubes.beingdisposed in essentially a.

singlgplane and in parallelv longitudinal relationship with eachother,.the outer surfacesof only; the adjacentmetalv tubes being incontact withfeachr other over substantiallyy only a line contact, eachofsaid metal tubes beingmetalli.- cally. andrigidly bonded to rits.adjacent metal tube over only a small area immediately adjacenttheirlines ofcontact to providea flrst path of good thermal conductivitybetween the adja-v centmetalltubes and to give rigidityto the heatIexchangev tubing.. structure, and metallic banding oflgoodthermalconductivity encompassing said metal' tubes, being partially crimped`about vsaid metal tubes andcontacting said metal tubes over asubstantialV area of their external surfaces and being metallically andfrigidlyV bonded to said metal tubes to provide a second path of goodthermal conductivity between the metaltubes,

and also to give rigidity to the heat" exchange tubing structure,therefbeingoppositely disposed separate air spaces dened by; portions ofthe outerjsurfacesof each of said metal tubes and thefinner surfaces ofthe crimpedportions of said metallic4 banding for collectingfluid from:said.

3. A prefabricated heat exchange tubing struc-- ture comprising at leasttwo individual metal tubes of generally rounded cross section, all ofsaid metal tubes being disposed in essentially a single plane and inparallel longitudinal relationship with each other, the outer surfacesof only the adjacent metal tubes being in contact with each other oversubstantially only a line contact, each of said metal tubes beingmetallically and rigidly bonded to its adjacent metal tube over only asmall area immediately adjacent their lines of contact to provide afirst path of good thermal conductivity between the adjacent metal tubesand to give rigidity to the heat exchange tubing structure, and metallicbanding of good thermal conductivity encompassing said metal tubes,contacting said metal tubes over a substantial area of their externalsurfaces and being metallically and rigidly bonded to said metal tubesto provide a second path of good thermal conductivity between the metaltubes and also to give rigidity to the heat exchange tubing structure,there being oppositely disposed separate air spaces defined by portionsof the outer surfaces of each of said metal tubes and the inner surfacesof said metallic banding for collecting fluid from said metal tubes inthe event of rupture of any of said metal tubes within the confines ofsaid metallic banding and adjacent the air spaces and for effectivelypreventing intermingling of the uids in said metal tubes upon suchrupturing of any of said metal tubes, said encompassing metallic bandingconsisting of a relatively nat and narrow metallic band helically woundaroundrsaid` tubes. withzthe-windingzonsaid, metallic band being'slightly;` spaced fromv each#- other to provideapertures-communicatingwith; said air spaces so that leakage fromsaid-metal tubes into any of said air spaces upon .rupture of any ofsaid metal tubes-may bereadily; de-

tected through said apertures from theexterior: of the prefabricatedheat exchange tubing;struc.

ture..

4. A prefabricated heat exchange tubing strucf ture comprising at leasttwo. individual metal,

tubes of generallyrounded cross section, all of said metal tubes beingdisposed in essentially a single plane and in parallel longitudinalrelationship with each other, the outer surfaces ofonlythe adjacentmetalV tubes being in contactiwith each.V

other over substantially only a line contact,.each of said metal tubesbeing *metallically and rigide lyfbonded to its adjacent metaltubeloverfonlyfa small areaimmediately adjacent'their lineswoi-l contactto provide a first path of good thermal conductivity between theadjacent. metal-tubes and to give rigidity to the heat exchange tubing;structure, yanclmetallic bandingof good thermal: conductivityencompassing said metal tubes, lcon.-` tacting said metal tubes overasubstantial area'` of theirr external surfaces and being metallicallyandnrigidly bonded to'said metal tubes toprovide' a second path of goodthermal conductivity-,be` tween the metal tubes and also togiverigidity;

to theheat exchange tubing structure,;there beA ing oppositely disposedseparate air spacesdefined byportions-of the outer surfaces of eachvof-said metal tubes and the inner surfaces of vsaid metallic banding forcollecting fluid from said metal tubes in the event of rupture of any ofsaid metal tubes within the confines of said metallic band ingandadjacent the air spaces and for effectivelyr preventing interminglingof the fluids. in said metal tubes upon such rupturingV of any of'said-r metaltubes, said encompassingmetallic banding:v

consisting of aerelatively flat and nar-rowfmetallic bandhelicallyvwound aroundy said tubes and'having holes spaced therealong toprovide apertures communicating with said air spaces so that leakagefrom said metal tubes into any of said air spaces upon rupture of any ofsaid metal tubes may be readily detected through said apertures from theexterior of the prefabricated heat exchange tubing structure.

5. A prefabricated heat exchange tubing structure comprising at leasttwo individual metal tubes of generally rounded cross section, all ofsaid metal tubes being disposed in essentially a single plane and inparallel longitudinal relationship with each other, the outer surfacesof only the adjacent metal tubes being in contact with each other oversubstantially only a line contact, each of said metal tubes beingmetallically and rigidly bonded to its adjacent metal tube over only asmall area immediately adjacent their lines of contact to provide afirst path of good thermal conductivity between the adjacent metal tubesand to give rigidity to the heat exchange tubing structure, and metallicbanding of good thermal conductivity encompassing said metal tubes,contacting said metal tubes over a substantial area of their externalsurfaces and being metallically and rigidly bonded to said metal tubesto provide a second path of good thermal conductivity between the metaltubes and also to give rigidity to the heat exchange tubing structure,there being oppositely disposed separate air spaces defined by portionsof the outer surfaces of each of said metal tubes and the inner surfacesacentos 'l of 'said metallic banding for collecting fluid from saidmetal tubes in the event of rupture of any of said metal tubes Withinthe connes of said metallic banding and adjacent the air spaces and foreffectively preventing intermingling of the fluids in said metal tubesupon such ruptur ing of any of said metal tubes, said encompassingmetallic banding consisting of a series of individual relatively nat andnarrow metallic bands encompassing said metal tubes and spaced slightlyfrom each other to provide apertures communicating With said air spacesso that leakage from said metal tubes into any of said air spaces uponrupture of any of said metal tubes may be readily detected through saidapertures from the exterior of the prefabrcated heat exchange tubingstructure. Y

6. A prefabricated heat exchange tubing structure' comprising at leasttw-o individual metal tubes of generally rounded cross section, all ofsaid metal tubes being disposed in essentially a single plane and inparallel longitudinal relation- :ship with each other, the outersurfaces of only the adjacent metal tubes being in contact with veachother over substantially only a line contact, each of said metal tubesbeing metallically and rigidly bonded to its adjacent metal tube overonly a small area immediately adjacent their lines of contact to providea rst path of good thermal conductivity between the adjacent metal tubesand to give rigidity to the heat exchange tubing structure, and metallicbanding of good thermal conductivity encompassing said metal tubes,contacting said metal tubes over a substantial area of their externalsurfaces and beo ing metallically and rigidly bonded to said metal tubesto provide a second path of good thermal conductivity between the metaltubes and also to give rigidity to the heat exchange tubing structure,there being oppositely disposed separate air spaces defined by portionsof the outer surfaces of each of said metal tubes and the inner surfacesof said metallic banding for collecting fluid from said'metal tubes inthe event ofiupture of any of said metal tubes within the confines ofsaid metallic banding and adjacent the air spaces and for effectivelypreventing intermingling of the uids in said metal tubes upon suchrupturing of any of said metal tubes, said encompassing metallic bandingconsisting of' a series of individual relatively flat and narrowmetallic bands encompassing said metal tubes, each said metallic bandbeing provided with holes spaced therealong to provide aperturescommunicating with said air spaces so that leakage from said metal tubesinto any of said air spaces upon rupture of any of said metal tubes maybe readily detected through said apertures from the exterior of theprefabricated heat exchangel tubing structure.

IRVING H. COHLER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,799,706 Jacobus Oct. 28, 1930 n2,032,413 Hall Mar. 3, 1936 2,297,146 Guirl Sept. 29, 1942 2,297,165Ringel Sept. 29, 1942 2,443,295 Bisch June 15, 1948 FOREIGN PATENTSNumber Country Date 18,212 Great Britain Aug. 12, 1912 275,028 GreatBritain Aug. 4, 1927 152,795 Germany June 25, 1904 236,648 SwitzerlandJuly 2, 1945 OTHER REFERENCES Publication; Fedders News, published byFedders Radiator Co., Buffalo, New York, February 1940.

